The Quark Gluon Plasma (QGP) produced in ultra relativistic heavy-ion collisions at the Large Hadron Collider (LHC) can be studied by measuring the modifications of jets formed by hard scattered partons which interact with the medium. We studied these modifications via angular correlations of jets with charged hadrons for jets with momenta 20 < $p_{\rm{T}}^{\rm{jet}}$ < 40 GeV/$c$ as a function of the associated particle momentum. The reaction plane fit (RPF) method is used in this analysis to remove the flow modulated background. The analysis of angular correlations for different orientations of the jet relative to the second order event plane allows for the study of the path length dependence of medium modifications to jets. We present the dependence of azimuthal angular correlations of charged hadrons with respect to the angle of the axis of a reconstructed jet relative to the event plane in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 2.76 TeV. The dependence of particle yields associated with jets on the angle of the jet with respect to the event plane is presented. Correlations at different angles relative to the event plane are compared through ratios and differences of the yield. No dependence of the results on the angle of the jet with respect to the event plane is observed within uncertainties, which is consistent with no significant path length dependence of the medium modifications for this observable.

The near-side and away-side yield vs $p_{T}^{assoc}$ for $20<p_T^{jet}<40$ GeV/$c$ full jets of 30-50% centrality in Pb-Pb collisions. The background uncertainty is non-trivially correlated point-to-point. The correlated systematic uncertainties come from the shape uncertainty of the acceptance correction. There is an additional 5% global scale uncertainty.

The differences between out-of-plane and in-plane yields and mid-plane and in-plane yields on near-side and away-side vs $p_{T}^{assoc}$ for $20<p_T^{jet}<40$ GeV/$c$ full jets of 30-50% centrality in Pb-Pb collisions. The background uncertainty is non-trivially correlated point-to-point. The correlated systematic uncertainties come from the shape uncertainty of the acceptance correction. There is an additional 5% global scale uncertainty.

The ratios of out-of-plane to in-plane yields and mid-plane to in-plane yields on near-side and away-side vs $p_{T}^{assoc}$ for $20<p_T^{jet}<40$ GeV/$c$ full jets of 30-50% centrality in Pb-Pb collisions. The background uncertainty is non-trivially correlated point-to-point. The correlated systematic uncertainties come from the shape uncertainty of the acceptance correction.

The widths of near-side peaks for trigger jets in-plane, mid-plane, and out-of-plane vs $p_{T}^{assoc}$ for $20<p_T^{jet}<40$ GeV/$c$ full jets of 30-50% centrality in Pb-Pb collisions. The background uncertainty is non-trivially correlated point-to-point. The correlated systematic uncertainties come from the shape uncertainty of the acceptance correction.

The widths of away-side peaks for trigger jets in-plane, mid-plane, and out-of-plane vs $p_{T}^{assoc}$ for $20<p_T^{jet}<40$ GeV/$c$ full jets of 30-50% centrality in Pb-Pb collisions. The background uncertainty is non-trivially correlated point-to-point. The correlated systematic uncertainties come from the shape uncertainty of the acceptance correction.

Measurements of K∗ (892) 0 and φ(1020)resonance production in Pb–Pb and pp collisions at √ sNN = 5.02 TeV with the ALICE detector at the Large Hadron Collider are reported. The resonances are measured at midrapidity (|y| < 0.5) via their hadronic decay channels and the transverse momentum (pT) distributions are obtained for various collision centrality classes up to pT = 20 GeV/c. The pT-integrated yield ratio K∗ (892) 0/K in Pb–Pb collisions shows significant suppression relative to pp collisions and decreases towards more central collisions. In contrast, the φ(1020)/K ratio does not show any suppression. Furthermore, the measured K∗ (892) 0/K ratio in central Pb–Pb collisions is significantly suppressed with respect to the expectations based on a thermal model calculation, while the φ(1020)/K ratio agrees with the model prediction. These measurements are an experimental demonstration of rescattering of K∗ (892) 0 decay products in the hadronic phase of the collisions. The K∗ (892) 0/K yield ratios in Pb–Pb and pp collisions are used to estimate the time duration between chemical and kinetic freeze-out, which is found to be ∼ 4–7 fm/c for central collisions. The pT-differential ratios of K∗ (892) 0/K, φ(1020)/K, K∗ (892) 0/π, φ(1020)/π, p/K ∗ (892) 0 and p/φ(1020) are also presented for Pb–Pb and pp collisions at √ sNN = 5.02 TeV. These ratios show that the rescattering effect is predominantly a low-pT phenomenon.

The inclusive J/$\psi$ meson production in Pb-Pb collisions at a center-of-mass energy per nucleon-nucleon collision of $\sqrt{s_{\rm NN}}$ = 5.02 TeV at midrapidity ($|y|$ < 0.9) is reported by the ALICE Collaboration. The measurements are performed in the dielectron decay channel, as a function of event centrality and J/$\psi$ transverse momentum $p_{\rm T}$, down to $p_{\rm T}$ = 0 GeV/$c$. The J/$\psi$ mean transverse momentum $\langle p_{\rm T} \rangle$ and $r_{\rm AA}$ ratio, defined as $\langle p^{\rm 2}_{\rm T} \rangle_{\rm PbPb}/\langle p^{\rm 2}_{\rm T} \rangle_{\rm pp}$, are evaluated. Both observables show a centrality dependence decreasing towards central (head-on) collisions. The J/$\psi$ nuclear modification factor $R_{\rm AA}$ exhibits a strong $p_{\rm T}$ dependence with a large suppression at high $p_{\rm T}$ and an increase to unity for decreasing $p_{\rm T}$. When integrating over the measured momentum range $p_{\rm T}$ < 10 GeV/$c$, the J/$\psi$ $R_{\rm AA}$ shows a weak centrality dependence. Each measurement is compared with results at lower center-of-mass energies and with ALICE measurements at forward rapidity, as well as to theory calculations. All reported features of the J/$\psi$ production at low $p_{\rm T}$ are consistent with a dominant contribution to the J/$\psi$ yield originating from charm quark (re)combination.

Inclusive J/$\psi$ $r_{\rm AA} = \langle p^{2}_{\rm T} \rangle_{\rm PbPb} / \langle p^{2}_{\rm T} \rangle_{\rm pp}$ in Pb$-$Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV at midrapidity as a function of the mean number of participant nucleons. The correlated systematic uncertainty due to the pp reference is not included and amounts to 4.7%, shown as the red box around unity in the paper figure.

Inclusive J/$\psi$ nuclear modification factor $R_{\rm AA}$ at midrapidity, integrated over $p_{\rm T}$, as a function of mean number of participating nucleons in Pb$-$Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV. The correlated systematic uncertainty due to the pp reference is not included and amounts to 6.9%, shown as the red box around unity in the paper figure.

Inclusive J/$\psi$ nuclear modification factor $R_{\rm AA}$ at midrapidity for $p_{\rm T} > 0.15$ GeV as a function of mean number of participating nucleons in Pb$-$Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV. The low-$p_{\rm T}$ interval is removed to reject J/$\psi$ from photo-production. The correlated systematic uncertainty due to the pp reference cross section is not listed and amounts to 6.9%, shown as the red box around unity in the paper figure.

Inclusive J/$\psi$ nuclear modification factor, $R_{\rm AA}$, at midrapidity in Pb$-$Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV as a function of transverse momentum, $p_{\rm T}$, for different centrality intervals. The systematic uncertianty from the pp reference, which is correlated with centrality and shown as grey band in the paper figure, is listed as sys,Reference. The systematic uncertainties on the $T_{\rm AA}$ which are correlated in $p_{\rm T}$ for each centrality bin are not listed and amount additionally to 2\%, 3\%, and 5\% for 0-20\%, 20-40\%, and 40-90\% centrality, respectively. These uncertainties are shown as boxes around unity in the paper figure.

The transverse momentum (pT) differential yields of (anti-)He3 and (anti-)H3 measured in p-Pb collisions at sNN = 5.02 TeV with ALICE at the Large Hadron Collider (LHC) are presented. The ratios of the pT-integrated yields of (anti-)He3 and (anti-)H3 to the proton yields are reported, as well as the pT dependence of the coalescence parameters B3 for (anti-)He3 and (anti-)H3. For (anti-)He3, the results obtained in four classes of the mean charged-particle multiplicity density are also discussed. These results are compared to predictions from a canonical statistical hadronization model and coalescence approaches. An upper limit on the total yield of 4He¯ is determined.

Integrated production yield obtained from the average of $^3\mathrm{He}$ and $^3\overline{\mathrm{He}}$ corrected for the spin degeneracy factor $(2J +1)$ for minimum-bias p--Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$

Mean transverse momentum obtained from the average of $^3\mathrm{He}$ and $^3\overline{\mathrm{He}}$ as a function of the mean charged-particle multiplicity density in p--Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$ TeV

Coalescence parameter $B_3$ calculated using the average of $^3\mathrm{He}$ and $^3\overline{\mathrm{He}}$ for events in 0$-$10% multiplicity class in p$-$Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$

Coalescence parameter $B_3$ calculated using the average of $^3\mathrm{He}$ and $^3\overline{\mathrm{He}}$ for events in 10$-$20% multiplicity class in p$-$Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$

Coalescence parameter $B_3$ calculated using the average of $^3\mathrm{He}$ and $^3\overline{\mathrm{He}}$ for events in 20$-$40% multiplicity class in p--Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$

Coalescence parameter $B_3$ calculated using the average of $^3\mathrm{He}$ and $^3\overline{\mathrm{He}}$ for events in 40$-$100% multiplicity class in p--Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$

Integrated production yield obtained from the average of $^3\mathrm{He}$ and $^3\overline{\mathrm{He}}$ for the different multiplicity classes and $\mathrm{INEL} > 0$ p--Pb collisions at $\sqrt{s_\mathrm{NN}} = 5.02$

The multiplicity dependence of electron production from heavy-flavour hadron decays as a function of transverse momentum was measured in p-Pb collisions at $ \sqrt{s_{\mathrm{NN}}} $ = 5.02 TeV using the ALICE detector at the LHC. The measurement was performed in the centre-of-mass rapidity interval −1.07 < y$_{cms}$< 0.14 and transverse momentum interval 2 < p$_{T}$< 16 GeV/c. The multiplicity dependence of the production of electrons from heavy-flavour hadron decays was studied by comparing the p$_{T}$ spectra measured for different multiplicity classes with those measured in pp collisions (Q$_{pPb}$) and in peripheral p-Pb collisions (Q$_{cp}$). The Q$_{pPb}$ results obtained are consistent with unity within uncertainties in the measured p$_{T}$ interval and event classes. This indicates that heavy-flavour decay electron production is consistent with binary scaling and independent of the geometry of the collision system. Additionally, the results suggest that cold nuclear matter effects are negligible within uncertainties, in the production of heavy-flavour decay electrons at midrapidity in p-Pb collisions.[graphic not available: see fulltext]

This paper presents the first measurements of the charge independent (CI) and charge dependent (CD) two-particle transverse momentum correlators $G_{2}^{\rm CI}$ and $G_{2}^{\rm CD}$ in Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 2.76 TeV by the ALICE collaboration. The correlators are measured as a function of pair separation in pseudorapidity ($\Delta \eta$) and azimuth ($\Delta \varphi$) and as a function of collision centrality. The correlator $G_{2}^{\rm CI}$ exhibits a longitudinal broadening while undergoing a monotonic azimuthal narrowing from peripheral to central collisions. By contrast, $G_{2}^{\rm CD}$ exhibits a narrowing along both dimensions towards central events. These features are not reproduced by models such as HIJING and AMPT. However, the observed narrowing of the correlators is expected to result from the stronger transverse flow profiles produced in more central collisions and the longitudinal broadening is predicted to be sensitive to momentum currents and the shear viscosity per unit of entropy density $\eta/s$ of the matter produced in the collisions. The observed broadening is found to be consistent with the hypothesized lower bound of $\eta/s$ and is in qualitative agreement with values obtained from anisotropic flow measurements.

Longitudinal width evolution with the number of participants of the two-particle transverse momentum correlation $G_{2}^{\rm CI}$ in Pb--Pb collisions at $\sqrt{s_{\rm NN}}=2.76\;\text{TeV}$. The widths are extracted from bi-dimensional (2D) or projection (1D) fits of the correlation function.

The differential invariant cross section as a function of transverse momentum ($p_\rm{T}$) of electrons from semileptonic heavy-flavour hadron decays was measured at midrapidity in proton-proton (pp) collisions at $\sqrt{s}$ = 5.02 TeV in the $p_\rm{T}$ interval 0.5-10 GeV/$c$, as well as the invariant yield in central (0-10%), semi-central (30-50%) and peripheral (60-80%) lead-lead (Pb-Pb) collisions at $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV in the $p_{\rm{T}}$ intervals 0.5-26 GeV/$c$ (0-10% and 30-50%) and 0.5-10 GeV/$c$ (60-80%). The modification of the electron yield with respect to what is expected for an incoherent superposition of nucleon-nucleon collisions is evaluated by measuring the nuclear modification factor $R_{\rm{AA}}$. The measurement of the $R_{\rm{AA}}$ in different centrality classes allows in-medium energy loss of charm and beauty quarks to be investigated. Moreover, the measured $R_{\rm{AA}}$ is sensitive to the modification of the parton distribution functions (PDF) in nuclei, like nuclear shadowing, which causes a suppression of the heavy-quark production at low $p_\rm{T}$ in heavy-ion collisions at LHC.

This article reports measurements of the $p_{\rm{T}}$-differential inclusive jet cross-section in pp collisions at $\sqrt{s}$ = 5.02 TeV and the $p_{\rm{T}}$-differential inclusive jet yield in Pb-Pb 0-10% central collisions at $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV. Jets were reconstructed at mid-rapidity with the ALICE tracking detectors and electromagnetic calorimeter using the anti-$k_{\rm{T}}$ algorithm. For pp collisions, we report jet cross-sections for jet resolution parameters $R=0.1-0.6$ over the range $20<p_{\rm{T,jet}}<140$ GeV/$c$, as well as the jet cross-section ratios of different $R$, and comparisons to two next-to-leading-order (NLO)-based theoretical predictions. For Pb-Pb collisions, we report the $R=0.2$ and $R=0.4$ jet spectra for $40<p_{\rm{T,jet}}<140$ GeV/$c$ and $60<p_{\rm{T,jet}}<140$ GeV/$c$, respectively. The scaled ratio of jet yields observed in Pb-Pb to pp collisions, $R_{\rm{AA}}$, is constructed, and exhibits strong jet quenching and a clear $p_{\rm{T}}$-dependence for $R=0.2$. No significant $R$-dependence of the jet $R_{\rm{AA}}$ is observed within the uncertainties of the measurement. These results are compared to several theoretical predictions.

The global polarization of the $\Lambda$ and $\overline\Lambda$ hyperons is measured for Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 2.76 and 5.02 TeV recorded with the ALICE at the LHC. The results are reported differentially as a function of collision centrality and hyperon's transverse momentum ($p_{\rm{T}}$) for the range of centrality 5-50%, $0.5 < p_{\rm{T}} <5$ GeV/$c$, and rapidity $|y|<0.5$. The hyperon global polarization averaged for Pb-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 2.76 and 5.02 TeV is found to be consistent with zero, $\langle P_{\rm{H}}\rangle$ (%) $\approx$ 0.01 $\pm$ 0.06 (stat.) $\pm$ 0.03 (syst.) in the collision centrality range 15-50%, where the largest signal is expected. The results are compatible with expectations based on an extrapolation from measurements at lower collision energies at RHIC, hydrodynamical model calculations, and empirical estimates based on collision energy dependence of directed flow, all of which predict the global polarization values at LHC energies of the order of 0.01%.

An improved value for the lifetime of the (anti-)hypertriton has been obtained using the data sample of Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}} = $ 5.02 TeV collected by the ALICE experiment at the LHC. The (anti-)hypertriton has been reconstructed via its charged two-body mesonic decay channel and the lifetime has been determined from an exponential fit to the d$N$/d($ct$) spectrum. The measured value, $\tau$ = 242$^{+34}_{-38}$ (stat.) $\pm$ 17 (syst.) ps, is compatible with all the available theoretical predictions, thus contributing to the solution of the longstanding hypertriton lifetime puzzle.

The study of the strength and behavior of the antikaon-nucleon (K¯N) interaction constitutes one of the key focuses of the strangeness sector in low-energy quantum chromodynamics (QCD). In this Letter a unique high-precision measurement of the strong interaction between kaons and protons, close and above the kinematic threshold, is presented. The femtoscopic measurements of the correlation function at low pair-frame relative momentum of (K+p⊕K−p¯) and (K-p⊕K+p¯) pairs measured in pp collisions at s=5, 7, and 13 TeV are reported. A structure observed around a relative momentum of 58 MeV/c in the measured correlation function of (K-p⊕K+p¯) with a significance of 4.4σ constitutes the first experimental evidence for the opening of the (K¯0n⊕K0n¯) isospin breaking channel due to the mass difference between charged and neutral kaons. The measured correlation functions have been compared to Jülich and Kyoto models in addition to the Coulomb potential. The high-precision data at low relative momenta presented in this work prove femtoscopy to be a powerful complementary tool to scattering experiments and provide new constraints above the K¯N threshold for low-energy QCD chiral models.

This work presents new constraints on the existence and the binding energy of a possible $\Lambda$-$\Lambda$ bound state, the H-dibaryon, derived from $\Lambda$-$\Lambda$ femtoscopic measurements by the ALICE collaboration. The results are obtained from a new measurement using the femtoscopy technique in pp collisions at $\sqrt{s}=13$ TeV and p-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV, combined with previously published results from p-Pb collisions at $\sqrt{s}=7$ TeV. The $\Lambda$-$\Lambda$ scattering parameter space, spanned by the inverse scattering length $f_0^{-1}$ and the effective range $d_0$, is constrained by comparing the measured $\Lambda$-$\Lambda$ correlation function with calculations obtained within the Lednicky model. The data are compatible with hypernuclei results and lattice computations, both predicting a shallow attractive interaction, and permit to test different theoretical approaches describing the $\Lambda$-$\Lambda$ interaction. The region in the $(f_0^{-1},d_0)$ plane which would accommodate a $\Lambda$-$\Lambda$ bound state is substantially restricted compared to previous studies. The binding energy of the possible $\Lambda$-$\Lambda$ bound state is estimated within an effective-range expansion approach and is found to be $B_{\Lambda\Lambda}=3.2^{+1.6}_{-2.4}\mathrm{(stat)}^{+1.8}_{-1.0}\mathrm{(syst)}$ MeV.

Production cross sections of muons from semi-leptonic decays of charm and beauty hadrons were measured at forward rapidity ($2.5<y<4$) in proton--proton (pp) collisions at a centre-of-mass energy $\sqrt{s}=5.02$ TeV with the ALICE detector at the CERN LHC. The results were obtained in an extended transverse momentum interval, $2 < p_{\rm T} < 20$ GeV/$c$, and with an improved precision compared to previous measurements performed in the same rapidity interval at centre-of-mass energies $\sqrt{s}= 2.76$ and 7 TeV. The $p_{\rm T}$- and $y$-differential production cross sections as well as the $p_{\rm T}$-differential production cross section ratios between different centre-of-mass energies and different rapidity intervals are described, within experimental and theoretical uncertainties, by predictions based on perturbative QCD.

This work presents the first experimental observation of the attractive strong interaction between a proton and a multi-strange baryon (hyperon) $\Xi^-$. The result is extracted from two-particle correlations of combined $\rm{p}-\Xi^{-}$$\oplus$$\rm{\overline{p}}-\overline{\Xi}^{+}$ pairs measured in p-Pb collisions at $\sqrt{s_{\rm{NN}}}=5.02$ TeV at the LHC with ALICE. The measured correlation function is compared with the prediction obtained assuming only an attractive Coulomb interaction and a standard deviation in the range $[3.6,5.3]$ is found. Since the measured $\rm{p}-\Xi^{-}$$\oplus$$\rm{\overline{p}}-\overline{\Xi}^{+}$ correlation is significantly enhanced with respect to the Coulomb prediction, the presence of an additional, strong, attractive interaction is evident. The data are compatible with recent lattice calculations by the HAL-QCD Collaboration, with a standard deviation in the range $ [1.8,3.7]$. The lattice potential predicts a shallow repulsive $\Xi^-$ interaction within pure neutron matter at saturation densities and this implies stiffer equations of state for neutron-rich matter including hyperons. Implications of the strong interaction for the modeling of neutron stars are discussed.

The coherent photoproduction of J/$\psi$ was measured in ultra-peripheral Pb-Pb collisions at a center-of-mass energy $\sqrt{s_{\rm{NN}}}=5.02$ TeV with the ALICE detector. The J/$\psi$ is detected via its dimuon decay in the forward rapidity region for events where the hadronic activity is required to be minimal. The analysis is based on an event sample corresponding to an integrated luminosity of about 750 $\mu$b$^{-1}$. The cross section for coherent J/$\psi$ production is presented in six rapidity bins, covering the interval $-4.0 < y < -2.5$. The results are compared with theoretical models for coherent J/$\psi$ photoproduction. The results indicate that gluon shadowing effects play a role in the photoproduction process. The ratio of $\psi'$ to J/$\psi$ coherent photoproduction cross sections was measured and found to be consistent with that measured for photoproduction off protons.

The correlations of identical charged kaons were measured in p-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV by the ALICE experiment at the LHC. The femtoscopic invariant radii and correlation strengths were extracted from one-dimensional kaon correlation functions and were compared with those obtained in pp and Pb-Pb collisions at $\sqrt{s}=7$ TeV and $\sqrt{s_{\rm NN}}=2.76$ TeV, respectively. The presented results also complement the identical-pion femtoscopic data published by the ALICE collaboration. The extracted radii increase with increasing charged-particle multiplicity and decrease with increasing pair transverse momentum. At comparable multiplicities, the radii measured in p-Pb collisions are found to be close to those observed in pp collisions. The obtained femtoscopic parameters are reproduced by the EPOS hadronic interaction model and disfavor models with large initial size or strong collective expansion at low multiplicities.

Measurements of anisotropic flow coefficients ($v_n$) and their cross-correlations using two- and multi-particle cumulant methods are reported in collisions of pp at $\sqrt{s} = 13$ TeV, p-Pb at $\sqrt{s_{_{\rm NN}}} = 5.02$ TeV, Xe-Xe at $\sqrt{s_{_{\rm NN}}} = 5.44$ TeV, and Pb-Pb at $\sqrt{s_{_{\rm NN}}} = 5.02$ TeV recorded with the ALICE detector. These measurements are performed as a function of multiplicity in the mid-rapidity region $|\eta|<0.8$ for the transverse momentum range $0.2 < p_{\rm T} < 3.0$ GeV/$c$. An ordering of the coefficients $v_2 > v_3 > v_4$ is found in pp and p-Pb collisions, similar to that seen in large collision systems, while a weak $v_2$ multiplicity dependence is observed relative to nucleus--nucleus collisions in the same multiplicity range. Using the novel subevent method, $v_{2}$ measured in pp and p-Pb collisions with four-particle cumulants is found to be compatible with that from six-particle cumulants. The symmetric cumulants $SC(m,n)$ calculated with the subevent method which evaluate the correlation strength between $v_n^2$ and $v_m^2$ are also presented. The presented data, which add further support to the existence of long-range multi-particle azimuthal correlations in high multiplicity pp and p-Pb collisions, can neither be described by PYTHIA8 nor by IP-Glasma+MUSIC+UrQMD model calculations, and hence provide new insights into the understanding of collective effects in small collision systems.

The measurements of the production of prompt ${\rm D^0}$, ${\rm D^+}$, ${\rm D^{*+}}$, and ${{\rm D^+_s}}$ mesons in proton--proton (pp) collisions at $\sqrt{s}=5.02$ TeV with the ALICE detector at the Large Hadron Collider (LHC) are reported. D mesons were reconstructed at mid-rapidity ($|y|<0.5$) via their hadronic decay channels ${\rm D}^0 \to {\rm K}^-\pi^+$, ${\rm D}^+\to {\rm K}^-\pi^+\pi^+$, ${\rm D}^{*+} \to {\rm D}^0 \pi^+ \to {\rm K}^- \pi^+ \pi^+$, ${\rm D^{+}_{s}\to \phi\pi^+\to K^{+} K^{-} \pi^{+}}$, and their charge conjugates. The production cross sections were measured in the transverse momentum interval $0<p_{\rm T}<36~\mathrm{GeV}/c$ for ${\rm D^0}$, $1<p_{\rm T}<36~\mathrm{GeV}/c$ for ${\rm D^+}$ and ${\rm D^{*+}}$, and in $2<p_{\rm T}<24~\mathrm{GeV}/c$ for ${{\rm D^+_s}}$ mesons. Thanks to the higher integrated luminosity, an analysis in finer $p_{\rm T}$ bins with respect to the previous measurements at $\sqrt{s}=7$ TeV was performed, allowing for a more detailed description of the cross-section $p_{\rm T}$ shape. The measured $p_{\rm T}$-differential production cross sections are compared to the results at $\sqrt{s}=7$ TeV and to four different perturbative QCD calculations. Its rapidity dependence is also tested combining the ALICE and LHCb measurements in pp collisions at $\sqrt{s}=5.02$ TeV. This measurement will allow for a more accurate determination of the nuclear modification factor in p-Pb and Pb-Pb collisions performed at the same nucleon-nucleon centre-of-mass energy.

Ratio of $\rm {D}^{*+}$ to $\rm{D}^{0}$ meson yield in pp collisions at $\sqrt{\rm{s_{NN}}}$=7 TeV in |y|<0.5 as a function of $p_{\rm T}$. The cross section for $\rm {D}^{0}$ in pp collisions at $\sqrt{\rm{s_{NN}}}$=7 TeV was updated with respect to Eur.Phys.J. C77 no.8 (2017)550 to account for the change of the world-average BR of $\rm{D^{0}}\rightarrow K\pi$ from ($3.93\% \pm 0.04$) to ($3.89\% \pm 0.04$).
Branching ratio of $\rm D^{+-}\rightarrow K{\rm{\pi}}{\rm{\pi}}$: 0.0389*0.677.
Branching ratio of $\rm{D^{0}}\rightarrow K\pi$ : 0.0389.

Ratios of $\rm {D}^{0}$-mesons production cross sections in pp collisions at $\sqrt{\rm{s_{NN}}}$=7 TeV and $\sqrt{\rm{s_{NN}}}$=5.02 TeV as a function of $p_{\rm T}$. The cross section for $\rm {D}^{0}$ mesons in pp collisions at $\sqrt{\rm{s_{NN}}}$=7 TeV was updated with respect to Eur.Phys.J. C77 no.8 (2017)550 to account for the change of the world-average BR of $\rm{D}^{0}\rightarrow K\pi$ from ($3.93\% \pm 0.04$) to ($3.89\% \pm 0.04$).
Branching ratio of $\rm{D}^{0}\rightarrow K\pi$ : 0.0389.

Ratios of $\rm {D}^{+}$-mesons production cross sections in pp collisions at $\sqrt{\rm{s_{NN}}}$=7 TeV and $\sqrt{\rm{s_{NN}}}$=5.02 TeV as a function of $p_{\rm T}$. The cross section for $\rm {D}^{+}$ mesons in pp collisions at $\sqrt{\rm{s_{NN}}}$=7 TeV was updated with respect to Eur.Phys.J. C77 no.8 (2017)550 to account for the change of the world-average BR of $\rm D^{+-}\rightarrow K{\rm{\pi}}{\rm{\pi}}$ from ($9.46\% \pm 0.24$) to ($8.98\% \pm 0.28$).
Branching ratio of $\rm D^{+-}\rightarrow K{\rm{\pi}}{\rm{\pi}}$ : 0.0898.

First Column: Production cross sections for prompt D mesons (D0, D+, D*+ and D_s) at mid-rapidity in |y|<0.5 and full pT range, in pp collisions at 5.02 TeV. The second (sys) error is from the luminosity uncertainty, the third (sys) error is from the branching-ratio uncertainty. For D+, D*+ and Ds, the fourth (sys) error is due to the extrapolation to pt=0.
Second column: value of <pT> of prompt D0 mesons in |y|<0.5. The first uncertainty is statistical, the second is the systematic uncertainty.

The transverse structure of jets was studied via jet fragmentation transverse momentum ($j_{\rm{T}}$) distributions, obtained using two-particle correlations in proton-proton and proton-lead collisions, measured with the ALICE experiment at the LHC. The highest transverse momentum particle in each event is used as the trigger particle and the region $3 < p_{\rm{Tt}} < 15$ GeV/$c$ is explored in this study. The measured distributions show a clear narrow Gaussian component and a wide non-Gaussian one. Based on Pythia simulations, the narrow component can be related to non-perturbative hadronization and the wide component to quantum chromodynamical splitting. The width of the narrow component shows a weak dependence on the transverse momentum of the trigger particle, in agreement with the expectation of universality of the hadronization process. On the other hand, the width of the wide component shows a rising trend suggesting increased branching for higher transverse momentum. The results obtained in pp collisions at $\sqrt{s}$ = 7 TeV and in p-Pb collisions at $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV are compatible within uncertainties and hence no significant cold nuclear matter effects are observed. The results are compared to previous measurements from CCOR and PHENIX as well as to Pythia 8 and Herwig 7 simulations.

The production yield of prompt D mesons and their elliptic flow coefficient $v_2$ were measured with the Event-Shape Engineering (ESE) technique applied to mid-central (10-30% and 30-50% centrality classes) Pb-Pb collisions at the centre-of-mass energy per nucleon pair $\sqrt{s_{\rm NN}} =5.02$ TeV, with the ALICE detector at the LHC. The ESE technique allows the classification of events, belonging to the same centrality, according to the azimuthal anisotropy of soft particle production in the collision. The reported measurements give the opportunity to investigate the dynamics of charm quarks in the Quark-Gluon Plasma and provide information on their participation in the collective expansion of the medium. D mesons were reconstructed via their hadronic decays at mid-rapidity, $|\eta|&lt;0.8$, in the transverse momentum interval $1

v_{2}{EP} vs. p_{T} of prompt D0 mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the rapidity interval |y|<0.8
The first (sys) error is the systematic uncertainty from the other sources
The second (sys) error is the systematic uncertainty from the B feed-down contribution.

v_{2}{EP} vs. p_{T} of prompt D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the rapidity interval |y|<0.8
The first (sys) error is the systematic uncertainty from the other sources
The second (sys) error is the systematic uncertainty from the B feed-down contribution.

v_{2}{EP} vs. p_{T} of prompt D*+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the rapidity interval |y|<0.8
The first (sys) error is the systematic uncertainty from the other sources
The second (sys) error is the systematic uncertainty from the B feed-down contribution.

v_{2}{EP} vs. p_{T} of average prompt D0, D+, D*+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the rapidity interval |y|<0.8
The first (sys) error is the systematic uncertainty from the other sources
The second (sys) error is the systematic uncertainty from the B feed-down contribution.

v_{2}{EP} vs. p_{T} of prompt D0 mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the 60% small-q_{2}^{TPC} sample in the rapidity interval |y|<0.8
The first (sys) error is the systematic uncertainty from the other sources
The second (sys) error is the systematic uncertainty from the B feed-down contribution.

v_{2}{EP} vs. p_{T} of prompt D0 mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the 20% large-q_{2}^{TPC} sample in the rapidity interval |y|<0.8
The first (sys) error is the systematic uncertainty from the other sources
The second (sys) error is the systematic uncertainty from the B feed-down contribution.

v_{2}{EP} vs. p_{T} of prompt D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the 60% small-q_{2}^{TPC} sample in the rapidity interval |y|<0.8
The first (sys) error is the systematic uncertainty from the other sources
The second (sys) error is the systematic uncertainty from the B feed-down contribution.

v_{2}{EP} vs. p_{T} of prompt D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the 20% large-q_{2}^{TPC} sample in the rapidity interval |y|<0.8
The first (sys) error is the systematic uncertainty from the other sources
The second (sys) error is the systematic uncertainty from the B feed-down contribution.

v_{2}{EP} vs. p_{T} of prompt D0 mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 30-50% in the 60% small-q_{2}^{TPC} sample in the rapidity interval |y|<0.8
The first (sys) error is the systematic uncertainty from the other sources
The second (sys) error is the systematic uncertainty from the B feed-down contribution.

v_{2}{EP} vs. p_{T} of prompt D0 mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 30-50% in the 20% large-q_{2}^{TPC} sample in the rapidity interval |y|<0.8
The first (sys) error is the systematic uncertainty from the other sources
The second (sys) error is the systematic uncertainty from the B feed-down contribution.

v_{2}{EP} vs. p_{T} of prompt D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 30-50% in the 60% small-q_{2}^{TPC} sample in the rapidity interval |y|<0.8
The first (sys) error is the systematic uncertainty from the other sources
The second (sys) error is the systematic uncertainty from the B feed-down contribution.

v_{2}{EP} vs. p_{T} of prompt D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 30-50% in the 20% large-q_{2}^{TPC} sample in the rapidity interval |y|<0.8
The first (sys) error is the systematic uncertainty from the other sources
The second (sys) error is the systematic uncertainty from the B feed-down contribution.

v_{2}{EP} vs. p_{T} of average prompt D0, D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the 60% small-q_{2}^{TPC} sample in the rapidity interval |y|<0.8
The first (sys) error is the systematic uncertainty from the other sources
The second (sys) error is the systematic uncertainty from the B feed-down contribution.

v_{2}{EP} vs. p_{T} of average prompt D0, D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the 20% large-q_{2}^{TPC} sample in the rapidity interval |y|<0.8
The first (sys) error is the systematic uncertainty from the other sources
The second (sys) error is the systematic uncertainty from the B feed-down contribution.

v_{2}{EP} vs. p_{T} of average prompt D0, D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 30-50% in the 60% small-q_{2}^{TPC} sample in the rapidity interval |y|<0.8
The first (sys) error is the systematic uncertainty from the other sources
The second (sys) error is the systematic uncertainty from the B feed-down contribution.

v_{2}{EP} vs. p_{T} of average prompt D0, D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 30-50% in the 20% large-q_{2}^{TPC} sample in the rapidity interval |y|<0.8
The first (sys) error is the systematic uncertainty from the other sources
The second (sys) error is the systematic uncertainty from the B feed-down contribution.

Ratio of v_{2}{EP} in the 60% small-q_{2}^{TPC} sample to the unbiased sample vs. p_{T} of average prompt D0, D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the rapidity interval |y|<0.8.

Ratio of v_{2}{EP} in the 20% large-q_{2}^{TPC} sample to the unbiased sample vs. p_{T} of average prompt D0, D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the rapidity interval |y|<0.8.

Ratio of v_{2}{EP} in the 60% small-q_{2}^{TPC} sample to the unbiased sample vs. p_{T} of average prompt D0, D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 30-50% in the rapidity interval |y|<0.8.

Ratio of v_{2}{EP} in the 20% large-q_{2}^{TPC} sample to the unbiased sample vs. p_{T} of average prompt D0, D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 30-50% in the rapidity interval |y|<0.8.

v_{2}{EP} vs. p_{T} of average prompt D0, D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the 60% small-q_{2}^{V0A} sample in the rapidity interval |y|<0.8
The first (sys) error is the systematic uncertainty from the other sources
The second (sys) error is the systematic uncertainty from the B feed-down contribution.

v_{2}{EP} vs. p_{T} of average prompt D0, D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the 20% large-q_{2}^{V0A} sample in the rapidity interval |y|<0.8
The first (sys) error is the systematic uncertainty from the other sources
The second (sys) error is the systematic uncertainty from the B feed-down contribution.

v_{2}{EP} vs. p_{T} of average prompt D0, D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 30-50% in the 60% small-q_{2}^{V0A} sample in the rapidity interval |y|<0.8
The first (sys) error is the systematic uncertainty from the other sources
The second (sys) error is the systematic uncertainty from the B feed-down contribution.

v_{2}{EP} vs. p_{T} of average prompt D0, D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 30-50% in the 20% large-q_{2}^{V0A} sample in the rapidity interval |y|<0.8
The first (sys) error is the systematic uncertainty from the other sources
The second (sys) error is the systematic uncertainty from the B feed-down contribution.

Ratio of v_{2}{EP} in the 60% small-q_{2}^{V0A} sample to the unbiased sample vs. p_{T} of average prompt D0, D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the rapidity interval |y|<0.8.

Ratio of v_{2}{EP} in the 20% large-q_{2}^{V0A} sample to the unbiased sample vs. p_{T} of average prompt D0, D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the rapidity interval |y|<0.8.

Ratio of v_{2}{EP} in the 60% small-q_{2}^{V0A} sample to the unbiased sample vs. p_{T} of average prompt D0, D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 30-50% in the rapidity interval |y|<0.8.

Ratio of v_{2}{EP} in the 20% large-q_{2}^{V0A} sample to the unbiased sample vs. p_{T} of average prompt D0, D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 30-50% in the rapidity interval |y|<0.8.

Ratio of v_{2}{SP} in the 60% small-q_{2}^{V0A} sample to the unbiased sample vs. p_{T} of charged particles in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the rapidity interval |eta|<0.8.

Ratio of v_{2}{SP} in the 20% large-q_{2}^{V0A} sample to the unbiased sample vs. p_{T} of charged particles in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the rapidity interval |eta|<0.8.

Ratio of v_{2}{SP} in the 60% small-q_{2}^{V0A} sample to the unbiased sample vs. p_{T} of charged particles in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 30-50% in the rapidity interval |eta|<0.8.

Ratio of v_{2}{SP} in the 20% large-q_{2}^{V0A} sample to the unbiased sample vs. p_{T} of charged particles in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 30-50% in the rapidity interval |eta|<0.8.

Ratio of the p_{T} distribution in the 60% small-q_{2}^{TPC} sample to the unbiased sample of prompt D0 mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the rapidity interval |y|<0.8.

Ratio of the p_{T} distribution in the 60% small-q_{2}^{TPC} sample to the unbiased sample of prompt D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the rapidity interval |y|<0.8.

Ratio of the p_{T} distribution in the 20% large-q_{2}^{TPC} sample to the unbiased sample of prompt D0 mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the rapidity interval |y|<0.8.

Ratio of the p_{T} distribution in the 20% large-q_{2}^{TPC} sample to the unbiased sample of prompt D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the rapidity interval |y|<0.8.

Ratio of the p_{T} distribution in the 60% small-q_{2}^{TPC} sample to the unbiased sample of prompt D0 mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 30-50% in the rapidity interval |y|<0.8.

Ratio of the p_{T} distribution in the 60% small-q_{2}^{TPC} sample to the unbiased sample of prompt D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 30-50% in the rapidity interval |y|<0.8.

Ratio of the p_{T} distribution in the 20% large-q_{2}^{TPC} sample to the unbiased sample of prompt D0 mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 30-50% in the rapidity interval |y|<0.8.

Ratio of the p_{T} distribution in the 20% large-q_{2}^{TPC} sample to the unbiased sample of prompt D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 30-50% in the rapidity interval |y|<0.8.

Ratio of the p_{T} distribution in the 60% small-q_{2}^{TPC} sample to the unbiased sample of average prompt D0, D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the rapidity interval |y|<0.8.

Ratio of the p_{T} distribution in the 20% large-q_{2}^{TPC} sample to the unbiased sample of average prompt D0, D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 10-30% in the rapidity interval |y|<0.8.

Ratio of the p_{T} distribution in the 60% small-q_{2}^{TPC} sample to the unbiased sample of average prompt D0, D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 30-50% in the rapidity interval |y|<0.8.

Ratio of the p_{T} distribution in the 20% large-q_{2}^{TPC} sample to the unbiased sample of average prompt D0, D+ mesons in Pb-Pb collisions at sqrt{s_{NN}}=5.02 TeV in the centrality class 30-50% in the rapidity interval |y|<0.8.

We present the first measurements of femtoscopic correlations between the K$^0_{\rm S}$ and K$^{\rm \pm}$ particles in pp collisions at $\sqrt{s}=7$ TeV measured by the ALICE experiment. The observed femtoscopic correlations are consistent with final-state interactions proceeding solely via the $a_0(980)$ resonance. The extracted kaon source radius and correlation strength parameters for K$^0_{\rm S}$K$^{\rm -}$ are found to be equal within the experimental uncertainties to those for K$^0_{\rm S}$K$^{\rm +}$. Results of the present study are compared with those from identical-kaon femtoscopic studies also performed with pp collisions at $\sqrt{s}=7$ TeV by ALICE and with a K$^0_{\rm S}$K$^{\rm \pm}$ measurement in Pb-Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ TeV. Combined with the Pb-Pb results, our pp analysis is found to be compatible with the interpretation of the $a_0(980)$ having a tetraquark structure instead of that of a diquark.

The ALICE Collaboration has measured the energy dependence of exclusive photoproduction of $J/\psi$ vector mesons off proton targets in ultra-peripheral p-Pb collisions at a centre-of-mass energy per nucleon pair $\sqrt{s_{\rm NN}} = 5.02$ TeV. The e$^+$e$^-$ and $\mu^+\mu^-$ decay channels are used to measure the cross section as a function of the rapidity of the $J/\psi$ in the range $-2.5 &lt; y &lt; 2.7$, corresponding to an energy in the $\gamma$p centre-of-mass in the interval $40 &lt; W_{\gamma\mathrm{p}}&lt;550$ GeV. The measurements, which are consistent with a power law dependence of the exclusive $J/\psi$ photoproduction cross section, are compared to previous results from HERA and the LHC and to several theoretical models. They are found to be compatible with previous measurements.

Differential cross sections as a function of rapidity for exclusive J/PSI photoproduction off protons in ultra-peripheral p-Pb collisions. The corresponding J/PSI photoproduction cross sections in bins of the GAMMA-P centre-of-mass, W(GAMMA P), are also presented.

We present the measurement of a new set of jet shape observables for track-based jets in central Pb-Pb collisions at $ \sqrt{s_{\mathrm{NN}}}=2.76 $ TeV. The set of jet shapes includes the first radial moment or angularity, g, the momentum dispersion, p$_{T}$D, and the difference between the leading and sub-leading constituent track transverse momentum, LeSub. These observables provide complementary information on the jet fragmentation and can constrain different aspects of the theoretical description of jet-medium interactions. The jet shapes were measured for a small resolution parameter R = 0.2 and were fully corrected to particle level. The observed jet shape modifications indicate that in-medium fragmentation is harder and more collimated than vacuum fragmentation as obtained by PYTHIA calculations, which were validated with the measurements of the jet shapes in proton-proton collisions at $ \sqrt{s}=7 $ TeV. The comparison of the measured distributions to templates for quark and gluon-initiated jets indicates that in-medium fragmentation resembles that of quark jets in vacuum. We further argue that the observed modifications are not consistent with a totally coherent energy loss picture where the jet loses energy as a single colour charge, suggesting that the medium resolves the jet structure at the angular scales probed by our measurements (R = 0.2). Furthermore, we observe that small-R jets can help to isolate purely energy loss effects from other effects that contribute to the modifications of the jet shower in medium such as the correlated background or medium response.

Ratio of fully corrected $g$ distributions pp collisions at $\sqrt{s} = 7$\,TeV for $R = 0.2$ in the range of jet $p_{\mathrm{T,jet}}^{\rm ch}$ of $40$--$60$\,GeV$/c$ and PYTHIA Perugia 11 simulations. The systematic uncertainty of $g$ is propagated to the ratio.

Ratio of fully corrected $LeSub$ distributions in pp
collisions at $\sqrt{s} = 7$\,TeV for $R = 0.2$ in the range of jet $p_{\mathrm{T,jet}}^{\rm ch}$ of $40$--$60$\,GeV$/c$ and PYTHIA 8 Tune 4C simulations. The systematic uncertainty of $LeSub$ is propagated to the ratio.

Ratio of fully corrected $LeSub$ distributions in pp collisions at $\sqrt{s} = 7$\,TeV for $R = 0.2$ in the range of jet $p_{\mathrm{T,jet}}^{\rm ch}$ of $40$--$60$\,GeV$/c$ and PYTHIA Perugia 11 simulations. The systematic uncertainty of $LeSub$ is propagated to the ratio.

Ratio of fully corrected $LeSub$ distributions in $0$--$10\%$ central Pb--Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$\,TeV for $R = 0.2$ in the range of jet $p_{\mathrm{T,jet}}^{\rm ch}$ of $40$--$60$\,GeV$/c$ and PYTHIA 8 simulations. The systematic uncertainty of $LeSub$ is propagated to the ratio.

The first measurement of dielectron ($\mathrm{e}^{+}\mathrm{e}^{-}$) production in central (0$-$10$\%$) Pb-Pb collisions at $\mathbf{\sqrt{{\textit{s}}_{\mathrm{NN}}}}$ = 2.76 TeV at the LHC is presented. The dielectron invariant-mass spectrum is compared to the expected contributions from hadron decays in the invariant-mass range $0 < m_{\mathrm{ee}}<3.5\ \mathrm{GeV}/\textit{c}^{2}$. The ratio of data and the cocktail of hadronic contributions without vacuum $\rho^{0}$ is measured in the invariant-mass range $0.15 < m_{\mathrm{ee}}<0.7\ \mathrm{GeV}/\textit{c}^{2}$, where an excess of dielectrons is observed in other experiments, and its value is $1.40 \pm 0.28\ (\mathrm{stat.}) \pm 0.08\ (\mathrm{syst.}) \pm 0.27\ (\mathrm{cocktail})$. The dielectron spectrum measured in the invariant mass range $0 < m_{\mathrm{ee}}<1\ \mathrm{GeV}/\textit{c}^{2}$ is consistent with the predictions from two theoretical model calculations that include thermal dielectron production from both partonic and hadronic phases with in-medium broadened $\rho^{0}$ meson. The fraction of direct virtual photons over inclusive virtual photons is extracted for dielectron pairs with invariant mass $0.1 < m_{\mathrm{ee}}<0.3\ \mathrm{GeV}/\textit{c}^{2}$, and in the transverse-momentum intervals $1<p_{\mathrm{T}, \mathrm{ee}}<2\ \mathrm{GeV}/\textit{c}$ and $2<p_{\mathrm{T}, \mathrm{ee}}<4\ \mathrm{GeV}/\textit{c}$. The measured fraction of virtual direct photons is consistent with the measurement of real direct photons by ALICE and with the expectations from previous dielectron measurements at RHIC within the experimental uncertainties.

Dielectron invariant-mass spectrum measured in central Pb-Pb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV. The statistical and systematic uncertainties of the data are represented by vertical bars and boxes.

Dielectron invariant-mass spectrum divided by the hadronic cocktail without the contribution from the vacuum $\rho^{0}$. The statistical and systematic uncertainties of data are represented by vertical bars and boxes.

Data-to-cocktail ratio as a function of the invariant-mass. In the hadronic cocktail, random correlations of dielectrons from charm decays are assumed to simulate the effects of the interaction between charm quarks and the medium. The statistical and systematic uncertainties of data are represented by vertical bars and boxes.

Direct photon ratio $R_{\gamma^{(*)}}=1+\gamma^{(*)}_{\mathrm{dir}}/\gamma^{(*)}_{\mathrm{decay}}$ measured using virtual photons in the centrality range 0$-$10$\%$. The statistical and systematic uncertainties of the data are represented by vertical bars and boxes.